Transistor-regulated direct current power supply with remote programming capabilities



C. G. DE BLASIO LATED June 23, 1964 3,138,752 UPPLY TRANSISTOR-REGU DIRECT CURRENT POWER S WITH REMOTE PROGRAMMING CAPABILITIES 2 Sheets-Sheet 1 Filed Nov. 24, 1958 w EOPUMJJOO A H mokom joo INVENTOR.

CONRAD G. DeBLASlO BY D M 2.2.50 ouum u rm u Ow Om 2 .oE

June 23, 1964 c. G. DE BLASIO 3,138,752

TRANSISTOR-REGULATED DIRECT CURRENT POWER SUPPLY WITH REMOTE PROGRAMMING CAPABILITIES Filed Nov. 24, 1958 2 Sheets-Sheet 2 0 OO a K 8 mpmfih (a rim- I 1% LI O o N REFERENCE SYSTEM I INVENTOR. g? CONRAD e.oeB| As|0 3 United States Patent 3,138,752 TRANSISTOR-REGULATED DIRECT CURRENT POWER SUPPLY WITH REMOTE PROGRAM- MING CAPABILITIES Courad G. De Blasio, Red Bank, NJ. (1 Throckmorton Ave., West Long Branch, NJ.)

Filed Nov. 24, 1958, Ser. No. 775,889

15 Claims. (Cl 32322) My invention relates to improvements in regulating methods and means for a direct current power source, and more particularly to such a regulating method and means wherein transistors are used to maintain a constant DC. output voltage across the load by regulating action accomplished, in part, by employment of one or more socalled degenerative or feed-back circuits.

In each of the Reissue Patents Nos. 24,598 and 24,800 issued to me February 10, 1959, and March 22, 1960, respectively, there is disclosed a regulated DC. power source of the general type comprising a detector or input comparator system, a reference system, an amplifier, and a series regulator or control element or system; and wherein vacuum-tube voltage-regulator circuits are used. In various DC. power sources or current-supply apparatus of the prior art, the more advantageous transistors or socalled semi-conductor elements have been substituted for the vacuum or electron tubes previously used, for voltage regulation. An example of such transistorized currentsupply apparatus is disclosed in Patent No. 2,751,549 issued June 19, 1956, to Fay H. Chase and assiged to Bell Telephone Laboratories. It is likewise, advantageous to substitute for or to replace the electron tubes used in the DC. power sources disclosed in my two patents aforesaid; by transistors. To do this, however, provisions must be made to overcome a number of differences or difiiculties, such as the following:

(a) Transistors or semi-conductor elements are generally current-operated, whereas electron tubes are, broadly speaking, voltage-operated.

(b) Transistors generally operate in a completely different range of voltage and current than is the case in operation of electron tubes.

(0) Transistors react to and show a substantial change or variation in performance characteristic with temperature variations, for which reason and to make the use of transistors practical, especial expedients must be resorted to.

(d) Particularly because transistors are generally current-operated, they do not have any current-free control terminal such as would be comparable to the grid of a vacuum or electron tube. This fact complicates the design of gain-producing transistor stages.

(e) Because of the relatively low physical mass of transistors and poor thermal coupling to the environment, as compared with electron tubes, occurrence of an overload of very brief duration such as on the order of milliseconds, might result in burn-out.

With the foregoing in mind, it is one of the objects of my invention to provide an improved DC. power source of the character referred to which has all the technical advantages of those disclosed in my aforesaid reissue patents but in which the more advantageous transistors are used in lieu of electron tubes, and in which provisions are made to overcome or to allow for the various difiiculties to be encountered in practical application or use ice of transistors and, particularly, to eliminate or to overcome in large part the troublesome burn-out referred to in paragraph e above.

Another object is the provision of an improved electronic circuit breaker embodying one or more transistors, and/ or the attainment of a prescribed method of operation whereby use of a transistor as a circuit breaker becomes practical.

Other objects and advantages will hereinafter appear.

For the purpose of illustrating my invention an embodiment thereof is shown in the drawings, wherein FIG. 1a is a simplified schematic diagram illustrative of a method or means for remote control, in FIG. 2';

FIG. 1b is an explanatory characteristic curve of a type of transistor used in FIGS. 2 and 2'; and

FIGS. 2 and 2', shown on different sheets, when fitted together or matched constitute the entire simplified schematic diagram of a DC. power source or system constructed and operating in accordance with my invention and embodying my improved electronic circuit breaker, such elements and parts of circuitry as will be obvious to those skilled in the art having been omitted for the sake of simplification of disclosure of the novel features or arrangements and the novel method steps claimed herein.

For the purposes of comparison and wherever it is feasible, the various connections, circuitry and components which correspond, at least in a general way, to each of the latter in my aforesaid Reissue Patents Nos. 24,598 and 24,800, are designated by the same respective reference numerals or characters used in these two patents.

With reference now to FIGS. 2 and 2', a main source 10 of alternating current supplies, through a continuously variable auto transformer 11, a transformer 12 and its associated rectifier and filter system 14 across the output lines 15 and 16a of which there is produced the source E of high voltage D.C., variable and unregulated. Also supplied from the main A.C. source 10 is an auxiliary transformer 17 which is coupled to an auxiliary rectifier and filter system 18 across the output lines 19 and 20a of which there is produced a source E of high voltage DC. for the reference and auxiliary circuits hereinafter referred to.

In FIG. 2' an input detector or comparator system 67 includes a balanced detector comprised of a pair of PNP transistors 35a and 35b whose respective bases 34 and 44 function as sensing elements each, normally, at zero potential with respect to a negative line 16b, grounded as indicated.

In normal operation, a double-pole single-throw switch 83 is closed to connect across positive output line 15 and negative line 2012 a constant-current divider or so-called bleeder to which the DC. output voltage E0 is applied and which comprises resistances R and R forming one arm of an electrical bridge configuration indicated by the dash-line rectangle B. Resistance R comprises the seriesconnected Vernier resistance 31a and the variable resistance 31b. Resistance R comprises the series-connected fixed resistance 32b and the variable, calibration resistor 320. The source of current E with the series regulator or control system C hereinafter more fully described forms the other arm of bridge B. By a connection 33 from the constant-current divider or bleeder R R to base 34 of transistor 35a, the latter is made to be responsive to any occurring variation in output voltage E0.

Transistors 35a and 35b, connected as shown, constitute or function as a balanced detector to sense the null points N and N of bridge B. There is the following relation, assuming the currents at the junction or null point N to be as given below.

where i is bleeder current, i is current flowing out of the transistor base 34, and i is current flowing to the negative output line 20b of the reference system. Assuming that the potential at the junction or null point N is substantially zero with respect to -Eo, there is the following relation.

Eewamfemwm.

Output voltage E0, therefore, can be expressed as Under ordinary conditions of circuitry and methods of operation such as are to be found in some of the various transistorized systems of the prior art; the desired, simple, linear relationship of output E to R as in Equation 7 above, is not present because although R might be fixed as it is in my improved system, i is neither constant nor easily predictable. In my improved system and method of operation this difliculty is circumvented by using resistances. of respective values to insure that bleeder current i is so large compared to i that i R in the above Equation 7 becomes negligible and can be ignored. To this end, the respective values of the resistances or resistors are taken or made so that the ratio of i to i is in the range from substantially 100 to substantially 1,000.

The potentials supplying the input comparator 67 must be very steady. There is available the constant reference potential E By using the PNP transistors 35a and 35b it is possible to supply the collector 36, through resistor R10, with negative potential from line 20b and to Supply the collector 42, through resistor R with negative potential from line 20c. Emitter potential is supplied by positive regulated voltage through a common coupling resistor R Voltage gain of a conventional emitter triode amplifier employing common emitter H-parameters may be expressed as follows:

where v K =Voltage gain.

B=Current gain.

h =Input resistance.

Y =Load admittance.

h =Reserve voltage gain.

S =A small constant depending on transistor parameters.

From the above equation it is to be noted that gain is largely dependent upon the admittance of the load. Taken with this, there is the condition that the input impedance of a conventional common emitter amplifier stage is very low.

In the DC. amplifier embodied in my improved system, continuous current flow is maintained from one stage to the next. For such purpose, PNP-NPN stages are cascaded. Transistor 24 is a conventional NPN common emitter amplifier and is supplied with emitter potential from the output negative side or line 20b (-E of the reference system, which is very stable. To permit positive cut-off it is required, for transistor 24, that the potential at the base 45 be somewhat negative with respect to the emitter potential supplied from E Such requirement would not be possible were the collector of transistor 35a and the emitter of transistor 24 returned to the same supply potential. Accordingly and as shown, the emitter of transistor 24 is returned to its supply potential (-E through a forward-connected diode CR-1 which has a very low forward A.C. impedance characteristic. This diode, under conditions whereat a small current is flowing through the same, therefor functions as a constant-voltage clement. Small leakages in the collectorto-emitter circuit of transistor 24 are adequate to maintain the operating condition required of diode CR1. By means of this novel arrangement, the base of transistor 24 can in the absence of current-flow, return fully to -E thereby using Be as a bias potential of the proper sign.

The transistor Q is connected as an emitter follower and is a PNP type to fulfill or to provide for the following needs or conditions:

(a) The complementary nature of the amplifier is continued.

(b) A high impedance load is presented to the collector of transistor 24, thus to convert the current gain of the stages transistor 35a, transistor 24; into voltage gain.

(0) Transistor Q is functional to develop a substantial amount of current drive for the following stages (d) The collector of transistor Q; Which is the last voltage-sensitive point of any importance, is also returned to the fixed, referenced potential (E That current gain of the first amplifying stage from transistor 35a to transistor 24 is converted into voltage gain, is evident from the following.

Let fl'=fl fi3 where ,8 equals current gain of the first stage from transistor 35a to transistor 24 and [3 equals current gain of the third stage. Voltage gain up to transistor Q therefore, can be expressed as follows.

Voltage gain up to Q =K 45' 1 where K equals voltage gain of the emitter follower Q and usually is close to 1.

Z; equals net load impedance presented to the collector of transistor 24.

G equals input conductance of the input stage.

From the above it will be noted that if the net load impedance 2.; presented to the collector of transistor 24 is high, the voltage gain up to transistor Q will be high. That this is so will be seen from typical characteristic curves of the given type of triode used herein, i.e., collector current plotted against collector voltage. In such a graphical presentation as shown in FIG. lb, the flat collector characteristic lines clearly demonstrate the pentode-like behavior of transistor 24. The load line shows a load resistance substantially lower than the collector resistance, which permits ignoring the aforesaid resistance.

The PNP transistor Q is a current-gain stage or emitter follower which drives the series elements constituted by the parallel-connected PNP transistors 21a and 21b, the latter being the output of the control system C. Positive and negative bias potentials are referenced about the line Eo.

The reference system shown and which provides the very stable reference potential E embodies an auxiliary regulator which includes the pair of transistors Q and Q connected, as shown, to form and to function as a balanced comparator system. The base of transistor Q is referenced through a diode or reference element CR-Ztl to the negative line 20b (E which is always negative with respect to the negative and grounded line 16b. The base of transistor Q is referenced through a diode or reference element CR-22 to the positive line 19 (+E Test points or terminals TP-1 and TP2 to the respective bases of transistors Q and Q permit the operator to monitor any voltage dilference between these two bases and, if there is found to be any such difference, to reduce the same to zero by adjusting rheostat R It can at any time, therefore, be made certain that the reference potential E is the sum of the two, respective reference potentials across diodes CR-20 and CR-22.

An important feature of my improved system takes into account the fact that signal-amplifier transistors are, mostly, available only for relatively low potentials. In my improved system and in spite of this limitation or operational restriction, such transistors are used and made to be functional for voltage-regulation or control with supply potentials of considerably higher values and with power elements available for hundreds of volts. In the arrangement shown, all signal transistors 35a, 35b, 24 and Q operate from or see only fixed low potentials which do not vary regardless of the relatively high potential applied from line 16a to the power collectors 21c, 21'c and so operate regardless of the output potential E0. The entire D.C. amplifier system rides with line E; this operating condition or performance characteristic being established by the circuitry wherein the negative line 16b is connected directly to terminal 79, and wherein the positive reference line 19 with null point N is connected directly to terminal 79 with switch 83 closed. The emitters of transistors Q and Q never depart from this potential by more than about 1 volt, since the base-to-emitter circuit of a transistor requires current but very little voltage. It is only the transistor power elements Q 21a and 2115 whose collectors return to the full supply potential of line 16a, as required by the particular regulator. Thus, the basic regulator can be used over any range of potentials and currents for which power elements are available.

In FIG. 1a there is shown the method or means by which remote control and/or sensing is possible. The two sensing points N and N are brought out. The load R is sensed at the power terminal 78 of +E0 through the control resistor R and point N is applied to the power terminal 79 of -E0. As above, the following relation is present.

nun E R2 From the above it will be seen that control follows a simple linear law and R may be located remotely with only two connecting leads. Points N and N need not be brought to the load unless complete remote sensing is desired.

Another important feature of my improved system takes into account the fact that transistors are very subject to burn-out. In FIG. 2', for example, if a short-circuit is applied across the output terminals 78 and 79, the regulator will call for a large current and the series elements 21a and 21b will be made fully conductive. Since the supply potential E is capable of delivering high current, it will not fall greatly so that the dissipation in the series element will be essentially EI where it is the shortcircuit current. Since this short-circuit current may be many times as great as the normal operating current, it is clear that the total dissipation can be many times as great as the design wattage. The series elements 21a and 21b will, therefore, flash up to destructive temperature in milliseconds and failure will occur. The means or circuitry for circumventing this very serious dilficulty is shown in FIG. 2'. The current for transistor 24 is passed through the collector-to-emitter circuit of an auxiliary transistor Q Furthermore, the current of the second stage 35b of the balanced input is returned through the base-to-emitter circuit of the same transistor Q Under normal operating conditions transistors 35a and 35b both draw current. Transistor Q, is switched fully on by the current of transistor 35b and the normal signal current from transistor 35a follows the path to the base 45 of transistor 24. Under normal conditions, all is in equilibrium and signal currents flow in normal fashion. Disturbing A.C. signals and transients are kept from arriving at transistor Q; by means of filter R C It will be assumed that point N of transistor 35a goes appreciably negative, such as would be the case from an inadequacy of output current due to overload or short-circuit. It is evident from tracing current flow that the emitter of transistor 3511 will go negative, taking the emitter of transistor 35b with it, thereby effectively applying a positive potential between the base-to-emitter of transistor 35b. This is a cut-off potential for a PNP transistor, and current flow in transistor 35b is interrupted. This interrupts current flow from the base-to-emitter circuit of transistor Q and the base is then returned to potential 20c through R thereby causing transistor Q, to cut-off. This, in turn, breaks the signal current flow through the collector-emitter circuit of transistor 24. In the absence of signal current, the bases of transistors Q Q 21a, and 21b are pulled towards positive bias potential +E thereby etfectively cutting off these elements. The bias resistors are made small enough so that all leakage currents are absorbed through them, thereby assuring cut-off. Since the output is now out off, line +Eo falls further and a stable condition is reached with the following conditions existing:

(14) There is no output current, because the series elements 21a and 21b are cut off.

(b) Transistor 35b is cut ofi.

(c) Transistors 24, Q Q Q 21a and 21b are also cut off.

The situation is stable in this condition and nothing further occurs until some attempt is made to restore matters to the former condition. Thus it is seen that essentially the circuit is capable of existing in two completely stable states, one in which all elements are conducting normally (normal operation resulting) and the other in which the output system is cut off in the presence of a fault, etc. Cut off is very rapid and depends primarily on the bandwidth of the amplifier and time constant relative to C R Typical operating time is about .001 second.

Additional elements CR-2, CR-3 and CR4 are in cluded to compress transients and DC. voltages which under some conditions will be additive across various transistor electrodes, thereby promoting failure. Resistive elements R and R are inserted in such manner as to limit currents in the signal chain to such an extent that burn-out in this chain is virtually impossible regardless of DC. conditions existing. Resistor R does not affect the operating gain of transistor Q since it is in the collector circuit and the transistor is pentode-like in its behavior. Thus, limiting is conveniently achieved without degradation of performance.

The novelty of structure, circuitry or arrangement, and operating action in my aforesaid electronic circuit breaker embodying one or more transistors, can be pointed out by considering the control system as a dual-path amplifier. As shown in FIG. 2', in normal operation signals progress over one of the paths, i.e., form the sensing transistor 35a to transistor 24, from the latter to transistor Q functioning as an emitter follower, and thence to the transistor power element or current-gain stage Q, from which the amplified signals go to the parallel-connected transistors 21a and 21b constituting the output of the series regulator or control system designated generally by the reference rcharacter C. The other path comprising transistors 35b and Or; is static since the collector current from the collector 42 of transistor 35b biases, through resistor R the base of transistor Q to a saturated on condition. Should the normally balanced pair of transistors 35a and 35b become sufficiently unbalanced with respect to each. other, due to an overload on the system, adisconnect signal proceeds from the collector 42 of transistor 35b to the base of transistor Q7, thus interrupting the flow of current through the collector-emitter circuit of transistor 24 and the collector of transistor Q the disconnect signal then proceeding through the forwardconnected diode CR-l to the negative reference line b (E It will therefore be seen that the amplifier and control system is essentially a dual-stability system, i.e., one. capable of existing or of being functional in either the normal state of operation or an overload state. Transistor Q7 is the circuit breaker itself, working in conjunction with transistors 35a, 35b and 24, as explained. After occurrence of an overload, return or resetting to the original operating state must be produced by some external means such as will now be described.

Reset may be achieved in a number of ways. For such purpose there are employed two three-pole switches Si and S the latter being ganged, as represented by the. dash line. The three switch positions are, respectively, Reset, Off, and On. In the On position, operation is normal, with switch 83 closed. The contacts across control resistor R are now open, and a protective resistor R otherwise in the collector circuit of series elements 21a and 21b, is shorted out. In the Oif position control resistor R is shorted, thereby reducing output voltage to zero. Also, the protective resistor R is now inserted in the collector circuit of the series elements 21a and 21b, and functions to prevent destructive {current surges from flowing in this collector circuit during subsequent switching. In the Reset position the connections established by switches S and S are identical to those in the Off position except that in the Reset position a resistor R is shunted from the collector supply of the series system 21a, 21b, to the emitter line 16b, thereby delivering suflicient output current to restore matters to normal but not sufficient to put destructive current through a. short. Thus, in addition to providing a convenient reset, swtiches S and S provide a convenient- On-Off system.

From all the foregoing it will be seen that the special and novel means disclosed herein for resetting eliminates or avoids the difficulty inherent in comparable systems of the prior art. When it is required in the latter to reset, in the process of turning on or reactivating the transistors they can burn out because without the provision for some such preventive method or means as is embodied in my improved system, there can readily occur transients of sufiicient magnitude to result in destruction of the transistors. In my improved method or system this difiiculty is avoided by use of an auxiliary current, bypassing the main series transistors so as to provide sufficient current to the output to promote reset. This would not be possible into a load of substantial magnitude. By employing the additional Off position between the On and Rese positions of switches S and S conditions are made such that in the process of progressing from On to Reset the control system is made to call for a zero output voltage. Thus, it is only necessary for the reset system to provide enough current to bring the output system up to zero potential (representing no current to the load). The reset current can thereby be made relatively small and non-destructive. This unique arrangement also provides a conventien't Off position. The use of a protectiveresistor R of large resistance in the series collectors is thus made possible since in the Off position no substantial current need be delivered by the series system. The limiting arrangement described 8 above and including elements (IR-2, CR-3 and CR4, in

combination with the other protective means described,

limits the maximum voltage transients that can be developed in the system. From data taken on the currents involved when clamps CR-2 and CR-3 operate, it is.

shown that in addition to the line being clamped all emitter followers succeeding this point in the amplifier will. be similarly clamped without resort to additional diodes.

Suitable adjustable means indicated at 68 for the auto transformer 11 and the adjustment indicated for resistor 31a, are connected. by suitable means represented by the dash line 69. Thus, the variable resistor 31a is gangedto the auto transformer 11 so as to provide precisely the correct input voltage for each output voltage demanded by the control system. Good trackingis possible because the output voltage is a linear function of resistance R If the system departs from perfect balance as the result of changes in the detector system 67, it is only necessary to apply metering means across null points N and N and then, by means of potentiomter 38, to adjust for zero potential between the two null points N and N When this is done the system error is eliminated and the output voltage E0 is then dependent only upon resist.- ances R and R and the reference potential E Thus the system, in addition to possessing extremely high inherent stability, can be made to contribute zero error by simply performing a null-balance check periodically. High quality control resistors should be used.

With regard to the input system, there is the relation an E2 R2 Thus, when the potential difference between N and N is zero, it is evident that for R equals 0, E0 equals 0, and so on, proportionately.

The potential terminals 84 and and current terminals 78 and 79 are separate, as shown, to accomplish the two, following, important purposes.

(1) With switch 83 open, a control resistor (R) may be inserted from terminal or post 73 to terminal or post 84 so as to determine the output voltage according. to the above relationship of E /E equaling R /R In this instance, of course, the negative terminal or post 79 and terminal or post 85 would, through a strap or short, be connected together as indicated in dash line. Thus, remote control is possible at any distance over a two terminal line, such as an insulated coaxial line. The voltage at all times will be determined by E0=KR derived from the simple relationship above, and wherein R is the resistance in ohms of the aforesaid control resistor R. Thus, the power system may be remotely controlled or programmed according to commands from a central control or automatic system.

(2) The strapping or short between the minus or negative terminal 79 and post 85 may be opened and a. lead taken from post 85 to the negative side of the load so as to eliminte lead drop by providing remote sensing; Thus, the voltage error may be sensed at any point pro vided these leads are sufficiently extended.

The double-pole single-throw switch 83 is connected as shown, for switching from local to remote use in the manner described above.

While the remote programming capability in my novel direct current power supply or source is a useful or advantageous feature it is to be understood that this feature is not a requirement and that Without the same the system or unit is completely operational as shown and described herein. Likewise, it is to be understood that while the electronic-circuit-breaker feature is a useful or desirable safety feature to prevent burn-out of the transistors upon occurrence of an overload or short, this safety or protective feature is not a requirement and that Without the same the system or unit is completely operational as shown and described herein.

Various modifications within the conception of those skilled in the art are possible without departing from the spirit of my invention or the scope of the claims.

I claim as my invention:

1. In a direct current power source of the character described, lines respectively positive and negative, output terminals for said lines, voltage-control means including a transistor series-connected in one of said lines, means for applying direct current input voltage across the respective input terminals of said lines, the potential at said negative line being fixed equivalent to a ground, a third line, means for applying across said negative line and said third line a reference potential under conditions whereat the potential of said third line is always negative with respect to the potential of said negative line, a first resistance and a second resistance series-connected with respect to each other and constituting jointly a constantcurrent divider connected across said third line and said positive line, said power source embodying an electrical bridgelike configuration wherein said input voltage with said voltage-control means and with said reference potential constitutes one arm of said bridgelike configuration and wherein said first resistance and said second resistance constitute the other arm of the latter, transistors connected to constitute an input comparator system wherein the respective bases of said last-named transistors are functional as sensing elements, one of said sensing elements being connected to said constant-current divider at an intermediate point of the latter, another of said sensing elements being connected to said third line, certain of the elements and means forming part of said power source electrically connecting said comparator system and said voltage-control means and being so coordinated in said power source and with respect to each other as to establish and maintain during normal operation of said power source null points substantially at said sensing elements and a condition of substantially zero potential between said negative line and each of said null points, an auxiliary transistor having a base-to-emitter circuit, and means connecting said base-to-emitter circuit of said auxiliary transistor with respect to one of said comparator transistors to render the latter non-conductive upon occurrence of a condition of overload applied across said terminals thus to cause said one of said comparator transistors to cutoff.

2. A power source of the character described and as defined in claim 1, said power source being further characterized by the fact that the respective values of resistance of said first and second resistances are such that the ratio of bleeder current to current from said one of said sensing elements is relatively high.

3. In a direct current power source of the character described, lines respectively positive and negative, output terminals for said lines, voltage-control means including a first transistor series-connected in one of said lines, means for applying direct current input voltage across the respective input terminals of said lines, the potential at said negative line being fixed equivalent to a ground, a third line, means for applying across said negative line and said third line a reference potential under conditions whereat the potential of said third line is always negative with respect to the potential of said negative line, resistances series-connected with respect to each other and constituting jointly a constant-current divider connected across said third line and said positive line, a balanced input system comprising a second transistor connected to said constant-current divider and constituting a stage of amplification, a third transistor forming part of said balanced input system and connected to said second transistor and constituting a second stage, a fourth transistor connected to said third transistor and constituting another stage of amplification, an auxiliary transistor, connection means between said fourth transistor and said auxiliary transistor whereby current from said fourth transistor passes through the collector-to-emitter circuit of said auxiliary transistor, and connection means between said third transistor and said auxiliary transistor whereby current of said third transistor is returned through the base-toemitter circuit of said auxiliary transistor thus to render said first transistor non-conductive in event of a short-circuit across said output terminals, and means electrically connecting said balanced input system and said voltage-control means and functional to correlate operating action of said balanced input system and said voltage-control means in such wise that said input line during normal operation of said power source is substantially zero with respect to the potential of said negative line.

4. In a direct current power source of the character described, lines respectively positive and negative, voltageoutput terminals for application of output voltage to load, a reference system for supplying a constant reference potential, a balanced comparator system electrically interposed between said terminals and said reference system and responsive to variation in said output voltage from a given potential, means connected to said comparator system and responsive to the latter to develop control signals in accordance with occurring variation in said output voltage, means for amplifying said control signals, and a control system connected to and supplied from said amplifying means and connected to one of said lines for applying the amplified control signals to the latter; said control system including a series element series-connected in said negative line, switch means forming part of said power source and connected in the circuitry thereof to establish operating action of the same, clamping means functional as a diode, and means connecting the latter between one of said terminals and said control element in such wise as to limit the maximum voltage transients possible to be developed in said circuitry below such value as would otherwise result in destruction of said control element incidental to the presence of switching transients set up during switching action of said switch means.

5. A power source of the character described and as defined by claim 4; said power source being further characterized by the fact that said series element is in the form of a transistor having a collector connected to said negative line.

6. In a direct current power source of the character described, lines respectively positive and negative and having voltage-output terminals for application of output voltage to load, a reference system having positive and negative output lines across which there is supplied a constant reference potential, said reference system including a source of positive regulated voltage, a balanced comparator system electrically interposed between said voltage-output terminals and said reference system and responsive to variation in said output voltage from a given potential, said comparator system embodying a pair of transistors each having a collector and an emitter, means connected to said comparator system and responsive to the latter to develop control signals in accordance with occurring variation in said output voltage, means for amplifying said control signals, a control system connected to and supplied from said amplifying means and connected to one of said first-named lines for applying the amplified control signals to the latter, resistors connected to said reference system and respectively to the collectors of said transistors thus to supply the latter with negative potential from said reference system, a common coupling resistor connected to the emitters of said transistors and to said second-named source to supply positive regulated voltage for emitter potential, said reference system embodying an auxiliary regulator including a second pair of transistors each having a base and connected in said reference system and with respect to each other to constitute and to function jointly in said reference system as a balanced comparator system, means including a first diode element and connecting one of said transistor bases to said negative line of said reference system and in such wise that said one of said transistor bases is, referenced through said first diode element to said negative line of said reference system, means including a second diode element and connecting the other of said transistor bases to said positive line of said reference system and in suchv wise that said other of said transistor bases is referenced through said second diode element to said positive line of said reference system, and means forming part of said reference system and connected to be functional? therein to establish the operating condition whereat said reference potential equals substantially the sum of the two. respective reference potentials across said first and second diode elements.

7. In a direct current power source of the character described, lines respectively positive and negative, voltage-output terminals for application of' output voltage to load, a reference system for supplying constant reference potentials, a balanced comparator system electricallyinterposed between said terminals and said reference system and responsive to variation in said output voltage from agiven potential, said comparator system including a transistor having a collector, means connected to said comparator system and responsive to the latter to develop control signals in accordance with occurring variation in said output voltage, said last-named means including a transistor having an emitter and a base, means connecting said transistors to said reference system and providing that said collector and said emitter are returned respectively to different supply potentials available from said reference system, means for amplifying said control signals, and a'controli system connected to and supplied from said amplifying means and connected to one of said lines for applying the amplified control signals to the latter, said control system including a series element in the form of a voltage-control transistor series-connected in one of said lines.

8. In a direct current power source of the character described, lines respectively positive and negative, volt= age-output terminals for application of output voltage to load, a reference system for supplying a constantreference potential, a balanced comparator system electrically interposed between said terminals and said reference system and responsive to variation in said output voltage from a given potential, saidcomparator system includ ing avfirst transistor, means connected to said comparator system and responsive to the latter to develop control signals in accordance with occurring variation in said output voltage and including a second transistor having a collector and connected and functional to effect current gain from said" first transistor to said second transistor, a third transistor having an emitter and having a base connected to said collector and constituting a relatively high net load impedance thus to result in high voltage gain up to said third transistor, the load resistance of'said second transistor being substantially lower than the collector resistance thereof, a fourth transistor having an emitter and connected to and functional as an emitter follower with respect to said third transistor and constituting a current-gain stage, anda control system connected to the emitter of said fourth transistor and driven by the latter, said control system including a voltage-control transistor, and connection means for applying the signal output from saidcontrol system to one of said lines.

9; In a direct current power source of the character described, lines respectively positive and negative, voltage-output terminals for application of output voltage to load, a reference system for supplying constant ref erence potentials, such potentials including fixed and relatively low'potentials constant irrespective of said output voltage and" other conditions of potential occurring in said power source, a balanced comparator system includ ing at least one transistor and electrically interposed between said terminals and said reference system and responsive to variation in said output voltage from a given potential, means including at least one transistor and connected to said comparator system and responsive tothe latter to develop control signals'in accordance with occurring variation in said output voltage, means for amplifyingsaid control signals andincluding at least one transistor, each of said transistors aforesaid being connected to said reference'system to operate from said fixed control system including a series element series-connected in said negative line, said element being in the form of a' voltage-control transistor having a collector connectedto return to said negative line.

10. In a direct current power source of the character described, lines respectively positive and negative, a pair of output potential terminals for application of output voltage to load and a pair of output current terminals separate one from the other, a reference system for supplying a constant reference potential, a balanced comparator system including at least one transistor and electrically interposed between said terminals and said reference system and responsive to variation in said output voltage from a given potential, means connected tosaid comparator system and responsive to the latter to develop control signals in accordance with occurring variation in said output voltage, means for amplifying saidcontrol signals, and a control system connected to and supplied from said amplifying meansand connected to one of said lines for applying the amplified control signals to the latter, said control system including a series element series-connected in said negative line, said series element being in the form of a voltage-control transistor.

11. In a control circuit of the character described for causing a transistor to function as a circuit breaker; a transistor for such' purpose and having a base and a collector-to-emitter circuit and a base-to-emitter circuit, a second transistor and a third transistor connected and correlated for operation balanced with respect to each other and under which condition both draw current, a fourth transistor having a base and a collector-emitter circuit, connection means for causing current for said fourth transistor to pass through saidcollector-to-ernitter circuit of said first-named transistor, connection means for causing return of the currentof said third transistor through said base-to-emitter circuit of said first-named transistor, connection means for causing the collector current from said third transistorto biassaid base of said first-named transistor for operation of the latter at least substantially to the saturation point of the same, connection means for causing application of normal current from said second transistor to said base of said fourth transistor, and means for making said control circuit responsive to the condition whereat said second and third transistors operate unbalanced substantially with respect to each other, said last-named means under said unbalanced condition being effective to cause application of a disconnect signal from said third transistor to said base of said first-named transistor thus to interrupt the flow of current through said collector-emitter circuit of said fourth transistor and said collector of said firstnamed transistor.

12. Ina direct current power source of the character described, lines respectively positive and negative, output terminals for said lines, voltage-control means including a transistor series-connected in one of said lines, means for applying direct current input voltage across the. respective input terminals of said lines, the potential at said negative line being fixed equivalent to a ground, a third line, means for applying across said negative line and said third line a reference potential under conditions whereat the potential of said third line is always negative with respect to the potential of said negative line, resistances series-connected with respect to each other and constituting jointly a constant-current divider connected across said third line and said positive line, transistors connected to constitute an input comparator system having an input line connected to said constant-current divider, an auxiliary transistor having a base-to-emitter circuit, means connecting said base-to-emitter circuit of said auxiliary transistor with respect to one of said comparator transistors to render the latter non-conductive upon occurrence of a condition of overload applied across said terminals thus to cause said one of said comparator transistors to cut-off, means electrically connecting said input comparator system and said voltage-control means and functional to correlate operating action of said input comparator system and said voltage-control means in such wise that said input line during normal operation of said power source is substantially zero with respect to the potential of said negative line, a power transistor connected in said source to constitute a current-gain stage for the same and having a collector connected for return to the supply potential of said negative line, said power transistor being connected for operation thereof responsive to signals from said comparator system, and a source of fixed and relatively low potential connected to said comparator for operation of the same and functional to supply said potential maintained fixed and relatively low irrespective of variation in the output potential of said source.

13. In a direct current power source of the character described, lines respectively positive and negative and having voltage-output terminals respectively positive and negative for application of output voltage to load, a reference system having positive and negative output lines each at a fixed potential and across which there is supplied a constant reference potential, a balanced comparator system electrically interposed between said terminals and said reference system and responsive to signals occurring at and applied to said comparator system in extent and in nature corresponding to occurring variations in said output voltage from a given potential, said comparator system embodying a pair of signal transistors connected one with respect to the other, amplifying means supplied from said comparator system and embodying a third signal transistor connected to be functional as a common-emitter amplifier, a fourth transistor supplied from said third transistor and connected to be functional as an emitter follower and to convert current gain from said third signal transistor into voltage gain, a first power transistor supplied from said fourth transistor, and a second power transistor supplied from said first power transistor to be driven by the latter and functional as a control element, said second power transistor being connected to one of said first-named lines for applying the amplified control signals to the latter, each of said signal transistors being connected to operate from one of said output lines of said reference system, said positive output line of said reference system being connected to said negative voltage-output terminal to be substantially at the same potential as the latter during operation.

14. In a direct current power source of the character described, lines respectively positive and negative and having voltage-output terminals respectively positive and negative for application of output voltage to load, a reference system having a positive output line and a negative output line across which there is supplied a constant reference potential, said reference system including first and second transistors connected one with respect to the other and each having a base and a collector and an emitter, a balanced comparator system electrically interposed between said terminals and said reference system and responsive to variations in said output voltage from a given potential, means connected to said comparator system and responsive to the latter to develop control signals in accordance with occurring variation in said output voltage, means for amplifying said control signals, a control system connected to and supplied from said amplifying means and connected to one of said firstnamed lines for applying the amplified control signals to the latter, means including a first diode element and connecting one of said transistor bases to said negative output line of said reference system, means including a second diode element and connecting the other of said transistor bases to the negative side of said reference system, each of said collectors being connected to and referenced from the negative side of said reference system, and adjustable resistance means common with respect to and connecting said emitters to said positive output line of said reference system, said resistance means being functional upon adjustment of the same to establish an operational condition wherein there is no voltage difference between said transistor bases.

' 15. In a direct current power source of the character described, lines respectively positive and negative, voltage-output terminals respectively positive and negative for application of output voltage to load, a reference system for supplying a constant reference potential and including a negative supply potential, a balanced comparator system electrically interposed between said terminals and said reference system and responsive to variation in said output voltage from a given potential, means connected to said comparator system and responsive to the latter to develop control signals in accordance with occurring variation in said output voltage, means for amplifying said control signals and including a transistor having an emitter, means including a forward-connected diode connecting said emitter to said negative supply potential, a control system connected to and supplied from said amplifying means and connected to one of said lines for applying the amplified control signals to the latter, said reference system including an output line always positive with respect to said negative supply line of said reference system and connected during operation to one of said output terminals; and connection means and components forming respectively operational parts of all means having a signal-amplifying function, said connection means and components being connected and correlated with respect to each other to establish an operating condition and performance characteristic residing in the fact that each of said signal-amplifying means is always referenced with respect to one of said output terminals and follows occurring variation in potential at the latter.

References Cited in the file of this patent lace and Raisbeck, The Bell System Technical Journal, April 1951, vol. 30, pages 381-417.

The Emitter Coupled Differential Amplifier, D. W. Slaughter, IRE Transactions, March 1956, pages 51-53. 

1. IN A DIRECT CURRENT POWER SOURCE OF THE CHARACTER DESCRIBED, LINES RESPECTIVELY POSITIVE AND NEGATIVE, OUTPUT TERMINALS FOR SAID LINES, VOLTAGE-CONTROL MEANS INCLUDING A TRANSISTOR SERIES-CONNECTED IN ONE OF SAID LINES, MEANS FOR APPLYING DIRECT CURRENT INPUT VOLTAGE ACROSS THE RESPECTIVE INPUT TERMINALS OF SAID LINES, THE POTENTIAL AT SAID NEGATIVE LINE BEING FIXED EQUIVALENT TO A GROUND, A THIRD LINE, MEANS FOR APPLYING ACROSS SAID NEGATIVE LINE AND SAID THIRD LINE A REFERENCE POTENTIAL UNDER CONDITIONS WHEREAT THE POTENTIAL OF SAID THIRD LINE IS ALWAYS NEGATIVE WITH RESPECT TO THE POTENTIAL OF SAID NEGATIVE LINE, A FIRST RESISTANCE AND A SECOND RESISTANCE SERIES-CONNECTED WITH RESPECT TO EACH OTHER AND CONSTITUTING JOINTLY A CONSTANTCURRENT DIVIDER CONNECTED ACROSS SAID THIRD LINE AND SAID POSITIVE LINE, SAID POWER SOURCE EMBODYING AN ELECTRICAL BRIDGELIKE CONFIGURATION WHEREIN SAID INPUT VOLTAGE WITH SAID VOLTAGE-CONTROL MEANS AND WITH SAID REFERENCE POTENTIAL CONSTITUTES ONE ARM OF SAID BRIDGELIKE CONFIGURATION AND WHEREIN SAID FIRST RESISTANCE AND SAID SECOND RESISTANCE CONSTITUTE THE OTHER ARM OF THE LATTER, TRANSISTORS CONNECTED TO CONSTITUTE AN INPUT COMPARATOR SYSTEM WHEREIN THE RESPECTIVE BASES OF SAID LAST-NAMED TRANSISTORS ARE FUNCTIONAL AS SENSING ELEMENTS, ONE OF SAID SENSING ELEMENTS BEING CONNECTED TO SAID CONSTANT-CURRENT DIVIDER AT AN INTERMEDIATE POINT OF THE LATTER, ANOTHER OF SAID SENSING ELEMENTS BEING CONNECTED TO SAID THIRD LINE, CERTAIN OF THE ELEMENTS AND MEANS FORMING PART OF SAID POWER SOURCE ELECTRICALLY CONNECTING SAID COMPARATOR SYSTEM AND SAID VOLTAGE-CONTROL MEANS AND BEING SO COORDINATED IN SAID POWER SOURCE AND WITH RESPECT TO EACH OTHER AS TO ESTABLISH AND MAINTAIN DURING NORMAL OPERATION OF SAID POWER SOURCE NULL POINTS SUBSTANTIALLY AT SAID SENSING ELEMENTS AND A CONDITION OF SUBSTANTIALLY ZERO POTENTIAL BETWEEN SAID NEGATIVE LINE AND EACH OF SAID NULL POINTS, AN AUXILIARY TRANSISTOR HAVING A BASE-TO-EMITTER CIRCUIT, AND MEANS CONNECTING SAID BASE-TO-EMITTER CIRCUIT OF SAID AUXILIARY TRANSISTOR WITH RESPECT TO ONE OF SAID COMPARATOR TRANSISTORS TO RENDER THE LATTER NON-CONDUCTIVE UPON OCCURRENCE OF A CONDITION OF OVERLOAD APPLIED ACROSS SAID TERMINALS THUS TO CAUSE SAID ONE OF SAID COMPARATOR TRANSISTORS TO CUT-OFF. 